In this video (https://www.youtube.com/watch?v=rOHxsZBD3Us), Michael Tomasello explains what sets humans apart from chimpanzees. Chimpanzees collaborate with each other only when there aren't any opportunities to compete. However, faced with the choice between competition and co-operation, children are able to choose co-operation. When children have to collaborate to earn a reward, they will often divide the spoils equally, even when the experiment is set up such that one child gets an unequal share. In one ingenious experiment, an adult drops something unexpectedly, and the child goes to pick it up and hands it back to the adult. When the adult throws the object intentionally, the child doesn't help the adult to get it back. This shows that the child is able to read the intention of the adult, and acts accordingly. In another version of the experiment, an adult is trying to put books into a cupboard, but does not open the cupboard doors, bumping into them repeatedly. The child sees this, and opens the door for the adult. He watches the adult's expression to confirm that this is what the adult wanted.